Why does pollen morphology vary? Evolutionary dynamics and morphospace occupation in the largest angiosperm order (Asterales)

JARDINE, PHILLIP E.; PALAZZESI, LUIS; TELLERÍA, M. CRISTINA; BARREDA, VIVIANA D.

NEW PHYTOLOGIST

WILEY-BLACKWELL PUBLISHING, INC

Año: 2022 vol. 234 p. 1075 - 1087

0028-646X

Summary Morphological diversity (disparity) is a key component of biodiversity and increasingly afocus of botanical research. Despite the wide range of morphologies represented by pollengrains, to date there are few studies focused on the controls on pollen disparity and morphospace occupation, and fewer still considering these parameters in a phylogenetic framework. Here, we analyse morphospace occupation, disparity and rates of morphological evolutionin Asterales pollen, in a phylogenetic context. We use a dataset comprising 113 taxa fromacross the Asterales phylogeny, with pollen morphology described using 28 discrete characters. The Asterales pollen morphospace is phylogenetically structured around groups of relatedtaxa, consistent with punctuated bursts of morphological evolution at key points in theAsterales phylogeny. There is no substantial difference in disparity among these groups oftaxa, despite large differences in species richness and biogeographic range. There is alsomixed evidence for whole-genome duplication as a driver of Asterales pollen morphologicalevolution. Our results highlight the importance of evolutionary history for structuring pollen morphospace. Our study is consistent with others that have shown a decoupling of biodiversityparameters, and reinforces the need to focus on disparity as a key botanical metric in its ownright.